1. Field of the Invention
This relates in general to the packaging art, and more particularly is concerned with a continuous reclosable plastic zipper of a type which is used to close the mouth of a bag or package, and which includes, either before or after the zipper relative to the mouth of the bag or package, a tamper-evident non-reclosable peel-seal feature.
2. Description of the Prior Art
In the use of plastic bags and packages, particularly for foodstuffs, it is important that the bag be hermetically sealed until the purchaser acquires the bag and its contents, takes them home, and opens the bag or package for the first time. It is then commercially attractive and useful for the consumer that the bag or package be reclosable so that its contents may be protected. Flexible plastic zippers have proven to be excellent for reclosable bags, because they may be manufactured with high-speed equipment and are reliable for repeated reuse. A typical zipper is one which has a groove at one side of the bag mouth and a rib at the other side, which rib may interlock into the groove when the sides of the mouth of the bag are pressed together. Alternatively, a member having a plurality of ribs may be on one side of the bag mouth, while a member having a plurality of channels may be on the other side, the ribs locking into the channels when the sides of the mouth of the bag are pressed together. In such a case, there may be no difference in appearance between the two members, as the ribs may simply be the intervals between channels on a strip which may lock into another of the same kind. In general, and in short, some form of male/female interengagement is used to join the two sides of the bag mouth together. The so-called members, or strips, are bonded in some manner to the material from which the bags themselves are manufactured.
Usually, pull flanges extend above the rib and groove strips, which pull flanges may be pulled apart for access to the interior of the bag.
Although flexible zippers of this variety are quite popular, they do not always prevent the inadvertent or unwelcome opening of a bag or package within the store, and various additions have been made to provide tamper-evident seals which would reveal when it has been opened prior to purchase.
It is clear then that, in spite of the fairly high state of development in this art, there are certain objectives which have not been fully met. In particular, tamper-evident non-reclosable peel seals in plastic bags of the prior art remain characterized by highly inconsistent opening forces. That is to say, the development of a tamper-evident non-reclosable peel seal requiring a reproducibly consistent opening force, large enough to obviate accidental or unintended opening, yet small enough that the bag itself may not be damaged during separation of the peel seal, has to date eluded those skilled in the art. At the same time, the requirement that the adhesive used to form the peel seal remain on only one side of the bag, without the formation of adhesive filaments across the bag opening, and not readhere when the bag is closed, has not been satisfied in the bags of the prior art.
It is accordingly an object of the present invention to provide an improved tamper-evident non-reclosable peel seal suitable for use with reclosable plastic zippers in plastic bags and other packages to provide a hermetic seal until the peel seal is opened for the first time, and to provide a peel seal which is non-reclosable after being opened.